Production of potassium nitrate



oct. 2o, 1936.

o. KsELlTz 2,057,957

PRODUCTION OF POTASSIUM NITRATE Filed May. 2, 1934 2() gaSeS and mere especially nitrogen dioxide being` a solution and dried. The chlorine is removed 20 `i Same temperature Sodium ,nitrate deCOInDOSeS verted into sodium chloride, the potassium chlo- 40 Patented Och 20, 1936 N .UNITED s'rA'rEs PATENT oFFlCE Application May 2, 11934,v Serial No. 723,482

l In' Germany May-31,` 1933 2 Claims. (Oryza-'402) *My invention relates tothe production of potasbe so chosen that the Vapor pressure is lower srium nitrate from sodium nitrate. It is an object than the percentage which corresponds to the of my invention to improve the processes hitherto vapor' pressure at thelowest temperature occurused in carrying through this reaction. ring in the process, so that the condensation of 1 5 The Conversion 0f Sodium nitrate into pOtaS- water or of nitrogen dioxide from the gas is ob- 5 Sillln nitrate 21S hithel'tO practiced, Was Carried viated.I A potassium chloride containing 3 to 5% through in hot COnCeIltrated Solutions, I'OlIl moisture may be applied directly Without any Con- Which the sodium chloride formed in the course densation arising.

of the double co-nversion with potassium chloride 1 am aware that it is 01d to react potassium is separated, While the solution is still hot. This chloride with nitrogen dioxide to form potassium 10 hot S0111ti0r1 must further be Cooled, the Washing nitrate. It is however new to replenish the ni- Water must be evaporated and the final product trugen dioxide consumed in this reaction by the dried- AS arilie a purified Sodium nitrate iS ilSed decomposition of sodium nitrate. In this step, es Starting materiel- The DTOCeSS aCCOIding t0 instead of puriiied sodium nitrate, a less highl5 the present invention is also based on the intergrade material including caliche or residual 15v action of sodium nitrate and potassium chloride, masses may be used, the contents of nitrogen of but the' DIOCeSS 0i COHVeISiOny i. e. the eXCheJnge these materials being thus utilized in a particof the nitrate and the chlorine radicles, is carried ularly economical manner. The final product is through by way of the gaseous phase, nitrous a solid body, which need not be separated from used as conversion agent, entering into reaction under the form of sodium chloride.

with the potassium chloride to form potassium In practicing my invention I may for instance nitrate and nitrosyl chloride or chlorine gas aoproceed as follows:-

cordmg to the equations Example 1 25 NaNo3+NoC1=NaC1+2NO2 25 KC1+2NO2=KNO3+NOC1 One of two reaction vessels, which are insulated against heat losses and provided with means for In another reaction chamber solid sodium niheating them by electricity to 250 C., is filled trate iS eted upOn With the DitIOSYl Chloride with sodium nitrate, the other one with the and/0r chlorine `formed in the rst stage of the equivalent quantity of potassium chloride. The 30 I'eeetiOn, whereby the quantity 0f nitrogen ditwo vessels are so arranged that the gases can be Oxide Originally present is regenerated and the sucked or forced by a fan from the sodium nichloline IeCOVeled under the OIm 0f Sodium trate to the potassium chloride and back to the chloride. This process, which comprises a cirsodium nitrate. On the process being started, the

culation of the gases in contact with sodium nifree spaces in the reaction chambers are filled 35 trate and thereafter with potassium chloride at with nitrogen dioxide. By causing circulation of the Seme temperature, the IlitI'Ogen dioxide 00nthe gases in the direction mentioned above, the tents being replenished from Solid Sodium nireaction proceeds within e few hours to the extrate, iS rendered DOSSible by the fact that at the tent that almost all of the sodium nitrate is conmore' readily than potassium nitrate. ride into potassium nitrate. Apart from the heat It L? posslble to quantltatwely react qmva'lent lost by radiation and convection no energy is lost quantlties of sodium nitrate and potassmm chloin this process. ride Without any variation of temperature and therefore without any heat losses. In the rev action with sodium nitrate a slightly elevated A ieaCtOn VeSSei SeiVlng t0 IeCeiVe the Sodium temperature (up to 300 0,) and in the reaction nitrate under the form of crude saltpeter (caliche with potassium chloride the same or a lower tem- Containing abOllt 25% NeNOs) WhlCh 1S Well 1nperature, down to room temperature, may be sulated against heat losses, is heated by means used. External heat is supplied to the system in of electric resistances or by means of heated 50 order to raise and maintain the temperature acgases to about 300 C. The other vessel contains cordingly. t the quantity, corresponding to the quantity of In carrying through this process, it is not necnitrate in the rst Vessel, of potassium chloride essary that water be strictly kept out. The percontaining about 5% water, as obtainedin the centage of moisture and of nitrogen dioxide may production of KCl. The temperature 1n th1s 55 Example 2 chamber may vary between 30 and 80 C. The free space in the vessels is lled with nitrogen dioxide. A fan serves for circulating the gases from the crude nitrate to the potassium chloride and for carrying the nitrosyl chloride formed in this latter chamber back to the crude nitrate. A heat exchanger inserted between the vessels serves to cool the hot NO2 formed in the decomposition of the sodium nitrate to the moderate temperature at which potassium nitrate is formed, the cold reaction gases being at the same time preheated to the temperature of the sodium nitrate decomposition. The conversion of the potassium chloride into potassium nitrate is ended yafter a few hours and the starting material spent almost completely.

Apart from the heat lost by radiation from the heated vessel and the heat 10st in the heat exchanger during heating of the circulating gases to the decomposition temperature, no external energy is required in this process.

The drawing is a flow sheet illustrating the process as described with reference to Example 2.

Various changes may be made in the details disclosed in the foregoing specification without departing from the invention or sacrificing the advantages thereof.

I claim:-

1. The method of producing potassium nitrate which comprises acting on potassium chloride with nitrogen dioxide at a temperature between room temperature and about 300 C., supplying heat to the mixture of nitrosyl chloride and chlorine leaving the KCl, conducting it at about 200-300 C. in contact with sodium nitrate, passing the hot NO2 in heat exchange relation with fresh NOCl and C12 formed in the reaction and causing the nitrogen dioxide formed in the reaction to act on a fresh portion of solid potassium chloride.

2. The process which comprises reacting potassium chloride with gaseous nitrogen dioxide at a temperature ranging from about 30 to 80 C. to produce potassium nitrate and a mixture of gaseous nitrosyl chloride and chlorine, heating said gaseous mixture and passing it in contact with crude sodium nitrate at a relatively higher temperature ranging from about 200 to 300 C. to form sodium chloride and nitrogen dioxide, and recycling said nitrogen dioxide back to the first step of the process.

OSKAR KASELITZ. 

